This invention relates to certain bridged Group 4 transition metal complexes possessing a unique bridging structure and to olefin polymerization catalysts obtained from such complexes. In one form, this invention embodies Group 4 transition metal complexes containing a unique bridged, or divalent ligand structure having two anionic, delocalized .pi.-bonded ligands attached thereto. In a second embodiment the invention relates to Group 4 transition metal complexes containing a unique bridged ligand containing one of the foregoing anionic, delocalized .pi.-bonded moieties and one anionic amido or phosphido moiety. In a third embodiment the invention relates to Group 4 transition metal complexes containing a unique bridged ligand containing two anionic amido and/ or phosphido groups. In all cases the unique bridge consists of either boron or aluminum atoms which are further ligated with nitrogen containing groups.
In Angew. Chem. Int. Ed. Enal., 36, 21, p2338-2340 (1997) and in Phosphorus, Sulfur, and Silicon, 124 & 125, p561-565 (1997) amido substituted boron bridged ferrocenophanes useful for forming poly(ferrocenes) by a ring opening polymerization were disclosed. The synthesis and characterization of Group 1 and 2 metal and tin complexes of 1,2-bis(dimethylamino)-1,2-di-9-fluorenyldiboranes were disclosed in Chem. Ber., 127, p1901-1908, (1994). Diboranes having structure similar to those employed in the foregoing study were disclosed by the same researchers in Eur. J. Inorg. Chem., p505-509 (1998). Ferrocenophane derivatives of similar bisboranes for further molecular property studies were disclosed by J. Organomet. Chem., 530 p117-120 (1997). In Organometallics, 16, p4546-4550 (1997) boron bridged ansa metallocene complexes including dimethylsulfide and phosphine adducts thereof of possible use in Ziegler-Natta-type olefin polymerizations were disclosed.
In the patent literature, bridged metal complexes for use as olefin polymerization catalyst components, including such complexes containing one or more boron atoms in the bridge are generically disclosed by EP-A-416,815 and WO 98/39369.